Techniques of quantitative autoradiography have been employed to gain insights to chemical mechanisms involved in the regulation of brain function. We will refine the method of quantitative autoradiography to allow more precise assessments of neurotransmitter receptors and drug binding sites in the central nervous system (CNS). Particular attention will be directed to the problem of quenching of tritium emissions by white matter, and we will establish criteria for introducing quench corrections in studies involving human tissue. We will extend studies on the quantitative autoradiography of monoamine uptake sites, utilizing the antidepressant compounds desmethylimipramine and imipramine to identify, respectively, uptake sites for norepinephrine (NE) and serotonin (5-HT). Studies will be conducted to examine the ontogeny of monoamine uptake sites, possible sex differences, regulation of these sites and their distribution in post-mortem human brain. Further studies will examine monoamine receptors, and compare the distribution of monoamine uptake sites and receptors. The ontogeny of betal and beta2 adrenergic receptors will be examined, as will the cellular location of these selective subtypes, using the selective neurotoxin ibotenic acid. The location of putative internalized beta adrenergic receptors will also be studied. A major new emphasis of the present proposal will be studies of possible differences in neurotransmitter receptors in post-mortem brain tissue from patients with Huntington's disease, schizophrenia and manic-depressive illness. Extensive studies will be conducted of alterations in thyrotropin releasing hormone (TRH) and receptors for TRH in spinal tissue of patients with amyotrophic lateral sclerosis (ALS). The results of these experiments should provide important new basic information about the location and regulation of neurotransmitter receptors in rat brain, and important new clinical information about possible changes in neurotransmitter receptors in neurological and psychiatric diseases.